Abu Nasr Muhammad ibn Muhammad al-Farabi (c. 870–950) was born at Farab in what is now southern Kazakhstan, trained in Baghdad, and spent his later life at the Hamdanid court in Aleppo and Damascus. In the Muslim world, Aristotle is the 'First Teacher' (al-Muallim al-Awwal); al-Farabi became the 'Second Teacher' (al-Muallim al-Thani), the second systematic thinker after Aristotle.

His work runs along three lines. First, logic: he brought Aristotle's Organon into Arabic and wrote extensive commentaries on categories and propositions. Second, metaphysics and psychology: his doctrine of the active intellect (intellectus agens) describes the human mind's relation to a transcendent reason — a framework later European scholasticism, including Aquinas, would inherit. Third, political philosophy: in the Mabadi' Ara' Ahl al-Madina al-Fadila (Opinions of the People of the Virtuous City) he transposed Plato's Republic onto Islamic political thought. The ideal city is led by a prophet-philosopher; its inhabitants cooperate organically toward a shared end. Its opposites are the ignorant, the dissolute, the perverted, and the unstable cities.

Farabi also wrote the Kitab al-Musiqi al-Kabir, the most comprehensive medieval Arab work on music theory. Ibn Sina cites him directly; Averroes' commentaries on Aristotle build on his logical tradition. The systematic form of Islamic philosophy was first laid out by al-Farabi.